991 research outputs found
Non-archimedean Yomdin-Gromov parametrizations and points of bounded height
We prove an analogue of the Yomdin-Gromov Lemma for -adic definable sets
and more broadly in a non-archimedean, definable context. This analogue keeps
track of piecewise approximation by Taylor polynomials, a nontrivial aspect in
the totally disconnected case. We apply this result to bound the number of
rational points of bounded height on the transcendental part of -adic
subanalytic sets, and to bound the dimension of the set of complex polynomials
of bounded degree lying on an algebraic variety defined over , in analogy to results by Pila and Wilkie, resp. by Bombieri and Pila.
Along the way we prove, for definable functions in a general context of
non-archimedean geometry, that local Lipschitz continuity implies piecewise
global Lipschitz continuity.Comment: 54 pages; revised, section 5.6 adde
Fonctions constructibles exponentielles, transformation de Fourier motivique et principe de transfert
We introduce spaces of exponential constructible functions in the motivic
setting for which we construct direct image functors in the absolute and
relative cases. This allows us to define a motivic Fourier transformation for
which we get various inversion statements. We define also motivic
Schwartz-Bruhat spaces on which motivic Fourier transformation induces an
isomorphism. Our motivic integrals specialize to non archimedian integrals. We
give a general transfer principle comparing identities between functions
defined by integrals over local fields of characteristic zero, resp. positive,
having the same residue field. Details of constructions and proofs will be
given elsewhere.Comment: 10 page
Motivic integration in all residue field characteristics for Henselian discretely valued fields of characteristic zero
We extend the formalism and results on motivic integration from
["Constructible motivic functions and motivic integration", Invent. Math.,
Volume 173, (2008) 23-121] to mixed characteristic discretely valued Henselian
fields with bounded ramification. We also generalize the equicharacteristic
zero case of loc. cit. by giving, in all residue characteristics, an axiomatic
approach (instead of only using Denef-Pas languages) and by using richer
angular component maps. In this setting we prove a general change of variables
formula and a general Fubini Theorem. Our set-up can be specialized to
previously known versions of motivic integration by e.g. the second author and
J. Sebag and to classical p-adic integrals.Comment: 33 pages. Final versio
Energy Balance in the Solar Transition Region. IV. Hydrogen and Helium Mass Flows With Diffusion
In this paper we have extended our previous modeling of energy balance in the
chromosphere-corona transition region to cases with particle and mass flows.
The cases considered here are quasi-steady, and satisfy the momentum and energy
balance equations in the transition region. We include in all equations the
flow velocity terms and neglect the partial derivatives with respect to time.
We present a complete and physically consistent formulation and method for
solving the non-LTE and energy balance equations in these situations, including
both particle diffusion and flows of H and He. Our results show quantitatively
how mass flows affect the ionization and radiative losses of H and He, thereby
affecting the structure and extent of the transition region. Also, our
computations show that the H and He line profiles are greatly affected by
flows. We find that line shifts are much less important than the changes in
line intensity and central reversal due to the effects of flows. In this paper
we use fixed conditions at the base of the transition region and in the
chromosphere because our intent is to show the physical effects of flows and
not to match any particular observations. However, we note that the profiles we
compute can explain the range of observed high spectral and spatial resolution
Lyman alpha profiles from the quiet Sun. We suggest that dedicated modeling of
specific sequences of observations based on physically consistent methods like
those presented here will substantially improve our understanding of the energy
balance in the chromosphere and corona.Comment: 50 pages + 20 figures; submitted to ApJ 9/10/01; a version with
higher resolution figures is available at http://cfa-www.harvard.edu/~avrett
Dimension dependence of correlation energies in twoâelectron atoms
Correlation energies (CEs) for twoâelectron atom ground states have been computed as a function of the dimensionality of space D. The classical limit Dââ and hyperquantum limit Dâ1 are qualitatively different and especially easy to solve. In hydrogenic units, the CE for any twoâelectron atom is found to be roughly 35% smaller than the realâworld value in the Dââ limit, and about 70% larger in the Dâ1 limit. Between the limits the CE varies almost linearly in 1/D. Accurate approximations to real CEs may therefore be obtained by linear interpolation or extrapolation from the much more easily evaluated dimensional limits. We give two explicit procedures, each of which yields CEs accurate to about 1%; this is comparable to the best available configuration interaction calculations. Steps toward the generalization of these procedures to larger atoms are also discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70213/2/JCPSA6-86-6-3512-1.pd
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